Radio frequency identification (RFID) is a system that involves identifying and tracking items using radio waves. Retailers and manufacturers first used RFID to control shipping and inventory of valuable items. But as the technology became less expensive to produce, RFID became more widely used to control inventory of less expensive items. The system can be helpful in preventing retail theft. RFID also has uses in other fields.
How RFID works.
Many kinds of RFID exist. But the most common type uses tiny embedded computer chips that contain identifying data and sometimes other information. Each computer chip is attached to an extremely small transmitting antenna. A computer chip and its accompanying antenna are known as an RFID tag. An RFID tag can be smaller than a grain of rice. Some tags are nearly paper-thin and the size of postage stamps. The tags can be attached either to the object being tracked or to the object’s packaging.
To read the information on an RFID tag, a device called a reader is used. The reader sends out radio waves, which prompt the tag to send back the information stored on its computer chip. The reader usually transmits the information read from the tag to a computer to be processed or stored in a database. The database may be within the reader itself. In some cases, the reader may send new data back to the tag. The new data either supplement or replace existing information on the tag. The distance from which a reader can read an RFID tag depends on many factors. These factors include the specific type of tag used and the frequencies of the radio waves involved.
An RFID tag that uses a computer chip can be active, passive, or semipassive. An active tag has its own power source, usually a battery, which is used to power the chip and send signals to the reader. A passive tag does not have its own power source. Instead, it receives energy needed to power the chip and transmit the data from a brief electromagnetic pulse sent out by the reader. A semipassive tag uses its own power source to run its chip, but uses power from the reader to send signals. Semipassive tags are also called semiactive tags. RFID tags with their own power sources are more expensive to make and harder to dispose of than completely passive tags. But they can transmit their radio signals longer distances. For these reasons, active and semipassive RFID tags are generally reserved for higher-cost items that need to be tracked over longer ranges.
In addition to identification data, an RFID tag may contain other information about the product. For example, a tag for a pharmaceutical product may inform the reader that the product has passed its expiration date and should be removed from the shelves.
Chipless RFID tags do not use computer chips. Instead, they use other kinds of technology to relay information from the tags to the reader. For example, one type of chipless RFID tag uses special fibers. When the reader sends radio waves to the tag, the arrangement of the fibers reflects back a portion of the waves. The specific pattern of the reflected waves can be used to identify the object associated with the tag. Another type of chipless RFID tag uses a microscopic amount of a variety of magnetic chemicals. When radio waves from the reader strike the tag, each chemical sends back a radio wave of distinct frequency. The combination of the frequencies from all the chemicals can then be used to identify the tagged object.
Chipless RFID tags are less expensive than tags with computer chips and can operate in a wider range of environments. However, chipless tags generally cannot hold as much data and must be read at close distances. Sometimes, chipless tags must be read with no obstacles between the tag and the reader.
Uses.
RFID tags have many uses besides product shipping and inventory control. For example, several kinds of identification cards and building security key cards use RFID tags. The tags are also used in some payment systems, such as devices that automatically register the passing of an automobile through a toll booth and charge the toll to the vehicle’s owner. Yet another use of RFID tags is to establish the start and finish times for runners in marathons. Some RFID tags are even implanted inside pets for identification purposes.
Privacy concerns.
Some people are concerned that widespread use of RFID tags may endanger people’s privacy. They argue that companies could use data from RFID tags to compile detailed information about individual consumers. Other people worry that companies could someday be able to track RFID tags at great distances, allowing them to collect data on personal habits and actions. However, most RFID tags today are effective only for short distances.
